Facebook users climbs to 250 million

Facebook founder Mark Zuckerberg says the number of people using the online social networking service has climbed to 250 million.

"The rapid pace of our growth is humbling and exciting for us," Zuckerberg said in a message posted at Facebook's official blog.

"For us, growing to 250 million users isn't just an impressive number; it is a mark of how many personal connections all of you have made."

Palo Alto, California-based Facebook was founded in 2004 and has become the most popular online social networking service, eclipsing News Corporation-owned MySpace.

On Monday, it was revealed that a Russian internet company is offering to buy $US100 million ($A124.8 million) worth of stock from Facebook employees in a deal that would value the fast-growing social network at $US6.5 billion ($A8.1 billion).

The Russian company, Digital Sky Technologies (DST), which invested $US200 million ($A249.5 million) in Facebook in May, is offering $US14.77 ($A18.43) per share of Facebook common stock.

The tender offer will close "some time in August," said Jennifer Gill, a DST spokeswoman.

Facebook chief executive Zuckerberg said at the time that the decision whether to sell stock was up to employees and that the offer "is recognition of Facebook's growth and progress towards making the world more open and connected."

US computer software giant Microsoft bought a 1.6 per cent stake in Facebook for $US240 million in 2007, a deal that valued the company at $US15 billion.

While its number of users has grown at an amazing clip, Facebook, unlike other web giants such as Amazon, eBay, Google and Yahoo!, has yet to prove how it is going to translate traffic into cash.

"As of today, 250 million people are using Facebook to stay updated on what's happening around them and share with the people in their lives," Zuckerberg said in the Wednesday blog post.

"As we celebrate our 250 millionth user, we are also continuing to develop Facebook to serve as many people in the world in the most effective way possible. This means reaching out to everyone across the world."